Efecto del ángulo microfibrilar en las características tecnológicas de la madera de Pinus pseudostrobus var. apulcensis

El ángulo microfibrilar es la inclinación de las microfibrillas de celulosa en la pared celular en relación al eje vertical de la célula. Esta característica contribuye en explicar las variaciones en propiedades físicas y mecánicas de la madera y fibra procesada. Pinus pseudostrobus var. apulcensis es una especie forestal nativa de México con importancia económica e industrial. Se seleccionaron al azar 10 árboles sanos de esta especie en una plantación en Texcoco, Estado de México, México. De cada árbol se extrajo un tarugo a 1,3 m de altura de fuste. Se midió el ángulo microfibrilar, la densidad básica (DB), la longitud de traqueidas  y la contracción volumétrica con el objetivo de determinar el efecto del ángulo microfibrilar sobre dichas características tecnológicas en esta madera. Se obtuvo un ángulo microfibrilar promedio de 28,8°; densidad básica promedio de 0,43 g·cm-3; longitud de traqueidas promedio de 3516 µm y contracción volumétrica promedio de 10,3 %.  Se ajustaron modelos aditivos generalizados entre el ángulo microfibrilar como variable explicativa y cada una de las tres variables respuesta por separado. Finalmente se ajustó un modelo aditivo generalizado para conocer el comportamiento de la densidad básica, longitud de traqueidas y contracción volumétrica en función del ángulo microfibrilar. Este modelo generado tuvo una capacidad explicativa de 88,2 %. La variable mejor explicada por el ángulo microfibrilar fue la longitud de traqueidas (capacidad explicativa de 83,3 %). Sería interesante observar si este comportamiento se presenta en otras especies de pino mexicanas

Xilotecnia of the wood of Acacia schaffneri from the state of hidalgo, Mexico

The genus Acacia spp belongs to the family Leguminosae, with more than 1300 species distributed naturally in all continents except Europe. In Mexico there are 85 species, of which 46 are endemic, most located in arid and semiarid regions, being Acacia coulteri and Acacia farnesiana the most widely distributed. The aim of this study was to determine the technological characteristics of the wood of Acacia schaffneri. To determine the anatomical characteristics, the methodology of Autonomous Chapingo University’s wood anatomy laboratory was used; for the physical properties, standards NOM EE-117-1981 and NMX-EE-167-1983 were used, and in calculating the mechanical properties the mathematical formulas were employed. The wood is reddish brown and has interlocked grain with diffuse porosity, aliform confluent parenchyma and in confluent bands, and crystals and gums. The proportion of cells was 11,87% vessel elements, 50,65% fibers 27,76% axial parenchyma and 9,81% ray parenchyma. Basic density was 880 kg/m3, tangential, radial, axial and volumetric shrinkage values were 10,57%; 4,97%; 0,10% and 15,82 % respectively, and fiber saturation point was 19,97%. The mechanical properties were very high, so it can be used in the manufacture of floors and in building constructions

Propiedades Físico-Mecánicas de una Guadua Mexicana (Guadua aculeata)

En este artículo se presentan las propiedades físicas y mecánicas del culmo de Guadua aculeata. El material de estudio se colectó en el predio “Las Margaritas”, Hueytamalco, Puebla, México. El marcado, derribo y ensayo se realizó tomando como referencia las normas ISO 22157-1 ISO e ISO/TR 22157-2. Se presentan valores promedio de los resultados para las secciones inferior, media y superior; se observa que la densidad básica (peso anhidro/volumen verde) varia de 560 a 660 kg/m3 de la base a la parte superior del culmo. Las contracciones totales promedio fueronde 13,9 % en espesor; 7,1 % en diámetro y 0,1 % en longitud. En el caso de las propiedades mecánicas se encontró que el esfuerzo máximo cortante varió de 6,0 a 10,5 MPa; el esfuerzo máximo en compresión paralela a la fibra incrementó de 28,2 a 56,7 MPa de la sección inferior a la superior y su módulo de elasticidad de 13,7 a 20,7 GPa.El módulo de ruptura en flexión de 51,9 a 79,6 MPa y su módulo de elasticidad de 15,1 a 24,1 GPa. La resistencia en tensión paralela a la fibra se incrementó de 58,5 a 92,2 MPa y el módulo de elasticidad en ese esfuerzo de 8,2 a 9,8 GPa. La especie estudiada tiene propiedades físicas, mecánicas y geométricas similares a la G. angustifolia quese utiliza en la construcción en países como Colombia, Costa Rica, Panamá, Venezuela y Ecuador.The physical and mechanical properties of Guadua aculeata culm are shown in this paper. The study material was collected from the locality “Las Margaritas” Hueytamalco, Puebla, Mexico. The marking, felling and testingwas performed with reference to ISO standards ISO 22157-1 and ISO/TR 22157-2. The average values of the results of low, middle and upper sections are shown; the basic density (dry weight / green volume) ranged from 560 to 660 kg/m3 of the lower to upper culm section. The average total contractions were 13,9% in thickness; 7,1% in diameterand 0,1% in length. In the case of mechanical properties were found that the maximum shear stress varies from 6,0 to10,5 MPa; the maximum stress in compression parallel to fiber increased from 28,2 to 56,7 MPa from low to top section and the modulus of elasticity from 13,7 to 20,7 GPa. The modulus of rupture in bending varies from 51,9 to 79,6 MPa and the modulus of elasticity from 15,1 to 24,1 GPa. The strength in tension parallel to the fiber also increased from 58,5 to 92,2 MPa and modulus of elasticity ranged from 8,2 to 9,8 GPa. The studied specie has the same physical, mechanical and geometric properties to G. angustifolia that it is used in the construction in countries how Colombia, Costa Rica, Panama, Venezuela and Ecuador

Forest Fires, Land Use Changes and Their Impact on Hydrological Balance in Temperate Forests of Central Mexico

Temperate forests play a fundamental role in the provision, regulation, and support of hydrological environmental services, but they are subject to constant changes in land use (clearing, overgrazing, deforestation, and forest fires) that upset the hydrological balance. Through scenarios simulated with the Water Evaluation and Planning (WEAP) hydrological model, the present study analyzes the effects of forest fires and land use changes on the hydrological balance in the microwatersheds of central Mexico. The land use changes that took place between 1995 and 2021 were estimated, and projections based on the current scenario were made. Two trend scenarios were proposed for 2047: one with a positive trend (forest permanence) and the other with a negative trend (loss of cover from forest fires). The results show that with permanence or an increase in forest area, the surface runoff would decrease by 48.2%, increasing the base flow by 37% and the soil moisture by 2.3%. If forest is lost, surface runoff would increase up to 454%, and soil moisture would decrease by 27%. If the current forest decline trends continue, then there will be negative alterations in hydrological processes: a reduction in the interception of precipitation by the canopy and an increase in the velocity and flow of surface runoff, among others. The final result will be a lower amount of water being infiltrated into the soil and stored in the subsoil. The provision of hydrological environmental services depends on the maintenance of forest cover

Record of Morchella tridentina in an Abies religiosa forest in Mexico and in vitro culture of its mycelium with obtaining sclerotia

Antecedentes y Objetivos: El género Morchella agrupa hongos ascomicetos, con varias especies comestibles de gran importancia alimenticia y biotecnológica. En China y Estados Unidos de América se han logrado cultivar exitosamente especies de Morchella de forma artificial hasta producir cuerpos fructíferos. Los objetivos del presente trabajo fueron identificar las especies de Morchella recolectadas en bosque de Abies religiosa, cultivar su micelio in vitro y propagarlo en granos de trigo. El presente estudio contribuye al conocimiento de la fase inicial necesaria para el posible cultivo artificial de este grupo de hongos. Métodos: Se recolectaron hongos en un bosque de Abies religiosa ubicado en Santo Tomás Apipilhuasco, Tepetlaoxtoc, Estado de México, México. Los hongos se identificaron (taxonómica- y molecularmente) y se realizaron aislamientos a partir de trozos de tejido del ascocarpo en medio papa dextrosa agar (PDA) y posteriormente se realizó su propagación en granos de trigo. Resultados clave: Las especies recolectadas fueron identificadas como Morchella tridentina y se logró el cultivo de micelio in vitro en medio PDA, así como su propagación en granos de trigo, en donde se observó la formación de esclerocios después de 21 días de inoculación. Las características del micelio que se cultivó in vitro variaron entre las cepas, no obstante que se aislaron de especímenes pertenecientes a una misma especie. Los especímenes deshidratados fueron depositados en el Herbario CHAP que pertenece a la Universidad Autónoma de Chapingo. Conclusiones: Debido a que las presentes cepas fueron capaces de formar esclerocios, podrían ser utilizadas para la producción de ascocarpos. Sin embargo, es conveniente continuar con la investigación, con el objetivo de determinar las condiciones óptimas (ambientales, sustratos y de inducción de la fructificación) para ese fin y lograr su cultivo artificial.Background and Aims: The genus Morchella groups ascomycete fungi, with several edible species of great nutritional and biotechnological importance. In China and the United States of America, species of Morchella have been artificially cultivated succesfully until producing fruiting bodies. The objectives of this work were: identify species of Morchella collected in an Abies religiosa forest, cultivate their mycelium in vitro and propagate them in wheat grains. The present study contributes to the knowledge of the initial phase necessary for the possible artificial cultivation of this group of fungi. Methods: Mushrooms were collected in an Abies religiosa forest located in Santo Tomas Apipilhuasco, Tepetlaoxtoc, Mexico State, Mexico. Fungi were identified (taxonomically and molecularly) and isolation was realized from pieces from sporome tissue in potato dextrose agar (PDA) medium, followed by propagation in wheat grains. Key results: The species collected were identified as Morchella tridentina and cultivation in vitro of mycelium in PDA was achieved as well as its propagation in wheat grains, where the formation of sclerotia was observed after 21 days of inoculation. The characteristics of the in vitro-cultured mycelium varied among strains, although they were isolated from specimens corresponding to the same species. The specimens were deposited in the CHAP Herbarium, Universidad Autónoma de Chapingo. Conclusions: Because of the presence of strains that are capable to form sclerotia, it could be used for ascocarp production. However, it is convenient to continue with this investigation with the objective of determining the optimal conditions (environmental, substrates, fruiting induction) for this aim and to achieve its artificial cultivation

Structure and tree diversity of secondary dry tropical forests in the Sierra de Huautla Biosphere Reserve, Morelos

"Se estudió la recuperación en riqueza, composición, estructura y diversidad arbórea en 3 condiciones de bosque tropical caducifolio secundario con diferente tiempo de abandono (C35, C45 y C65 años) en el sureste del estado de Morelos. En cada condición se establecieron 3 unidades de muestreo de 50 × 50 m (2,500 m2) y se midieron a todos los individuos ≥ 2.5 cm de diámetro normal (DN). En total se registraron 2,791 individuos, pertenecientes a 79 especies, 53 géneros y 30 familias. Fabaceae fue la familia con el mayor número de especies e individuos. C45 presentó la mayor riqueza de especies (57), seguida de C35 (48) y C65 (43). Las condiciones fueron diferentes (p < 0.0001) en área basal, altura total, DN y cobertura de copa. Las especies con mayores índices relativos de valor de importancia (IVIR) y de valor forestal (IVFR) fueron Pachycereus grandis (IVIR = 22.6, IVFR = 28.7), Amphipterygium adstringens (IVIR = 20.9, IVFR = 17.0), Lysiloma divaricatum (IVIR = 11.2, IVFR = 18.9) y Quercus glaucoides (IVIR = 10.5, IVFR = 13.1). Se encontraron diferencias altamente significativas (p < 0.001) entre condiciones de abandono para la heterogeneidad (Shannon-Wiener: H´), y valores significativamente (p < 0.05) mayores en C65 para el recíproco de Simpson (1/D), así como en C35 y C45 para los índices de Margalef (DMG) y α de Fisher (S). La semejanza florística (Sorensen: Is) fue máxima entre condiciones con menor tiempo de abandono (72%) y mínima con la condición de mayor tiempo (54%). El procedimiento de permutación de respuesta múltiple indicó diferencias significativas (p < 0.05) en la composición de especies entre condiciones tempranas (C35 y C45) y tardías (C65). Estos resultados explican el proceso de la sucesión secundaria en los bosques tropicales caducifolios del área de estudio y dan elementos para efectuar una mejor planificación de las actividades conducentes a su conservación.""The recovery in richness, composition, structure and tree diversity was studied in three conditions of secondary tropical deciduous forest with different time of abandonment (C35, C45 and C65 years) in the southeast of the state of Morelos. In each condition, three plots of 50 × 50 m (2,500 m2) were established and all individuals ≥ 2.5 cm of normal diameter (ND) were measured. In total, 2,791 individuals belonging to 79 species, 53 genera and 30 families were registered. Fabaceae was the family with the largest number of species and individuals. C45 had the highest species richness (57), followed by C35 (48) and C65 (43). The conditions were different (p < 0.0001) in basal area, total height, ND and crown coverage. The species with the highest relative value of importance (IVIR) and forest value (IVFR) were Pachycereus grandis (IVIR = 22.6, IVFR = 28.7), Amphipterygium adstringens (IVIR = 20.9, IVFR = 17.0), Lysiloma divaricatum (IVIR =11.2, IVFR = 18.9) and Quercus glaucoides (IVIR = 10.5, IVFR = 13.1). High significant differences (p < 0.001) between abandonment conditions were found for heterogeneity (Shannon-Wiener: H’), and highest significant values (p < 0.05) for Simpson reciprocal index (1/D) in C65, as well as to Margalef (DMG) and Fisher’s α (S) indexes in C35 and C45. The floristic similarity (Sorensen: Is) was highest among conditions with less time of abandonment (72%) and minimum with the condition of greater time (54%). The multiple response permutation procedure indicated significant differences (p < 0.05) in the species composition between early (C35 and C45) and late (C65) conditions. These results explain the process of secondary succession in the tropical deciduous forests of the study area and provide elements for improve planning of the activities leading to its conservation.

Eligibility criteria for Menopausal Hormone Therapy (MHT): a position statement from a consortium of scientific societies for the use of MHT in women with medical conditions. MHT Eligibility Criteria Group

This project aims to develop eligibility criteria for menopausal hormone therapy (MHT). The tool should be similar to those already established for contraception A consortium of scientific societies coordinated by the Spanish Menopause Society met to formulate recommendations for the use of MHT by women with medical conditions based on the best available evidence. The project was developed in two phases. As a first step, we conducted 14 systematic reviews and 32 metanalyses on the safety of MHT (in nine areas: age, time of menopause onset, treatment duration, women with thrombotic risk, women with a personal history of cardiovascular disease, women with metabolic syndrome, women with gastrointestinal diseases, survivors of breast cancer or of other cancers, and women who smoke) and on the most relevant pharmacological interactions with MHT. These systematic reviews and metanalyses helped inform a structured process in which a panel of experts defined the eligibility criteria according to a specific framework, which facilitated the discussion and development process. To unify the proposal, the following eligibility criteria have been defined in accordance with the WHO international nomenclature for the different alternatives for MHT (category 1, no restriction on the use of MHT; category 2, the benefits outweigh the risks; category 3, the risks generally outweigh the benefits; category 4, MHT should not be used). Quality was classified as high, moderate, low or very low, based on several factors (including risk of bias, inaccuracy, inconsistency, lack of directionality and publication bias). When no direct evidence was identified, but plausibility, clinical experience or indirect evidence were available, "Expert opinion" was categorized. For the first time, a set of eligibility criteria, based on clinical evidence and developed according to the most rigorous methodological tools, has been defined. This will provide health professionals with a powerful decision-making tool that can be used to manage menopausal symptoms

Impact of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients: A nationwide study in Spain

Objective To assess the effect of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients in Spain. Settings The initial flood of COVID-19 patients overwhelmed an unprepared healthcare system. Different measures were taken to deal with this overburden. The effect of these measures on neurosurgical patients, as well as the effect of COVID-19 itself, has not been thoroughly studied. Participants This was a multicentre, nationwide, observational retrospective study of patients who underwent any neurosurgical operation from March to July 2020. Interventions An exploratory factorial analysis was performed to select the most relevant variables of the sample. Primary and secondary outcome measures Univariate and multivariate analyses were performed to identify independent predictors of mortality and postoperative SARS-CoV-2 infection. Results Sixteen hospitals registered 1677 operated patients. The overall mortality was 6.4%, and 2.9% (44 patients) suffered a perioperative SARS-CoV-2 infection. Of those infections, 24 were diagnosed postoperatively. Age (OR 1.05), perioperative SARS-CoV-2 infection (OR 4.7), community COVID-19 incidence (cases/10 5 people/week) (OR 1.006), postoperative neurological worsening (OR 5.9), postoperative need for airway support (OR 5.38), ASA grade =3 (OR 2.5) and preoperative GCS 3-8 (OR 2.82) were independently associated with mortality. For SARS-CoV-2 postoperative infection, screening swab test <72 hours preoperatively (OR 0.76), community COVID-19 incidence (cases/10 5 people/week) (OR 1.011), preoperative cognitive impairment (OR 2.784), postoperative sepsis (OR 3.807) and an absence of postoperative complications (OR 0.188) were independently associated. Conclusions Perioperative SARS-CoV-2 infection in neurosurgical patients was associated with an increase in mortality by almost fivefold. Community COVID-19 incidence (cases/10 5 people/week) was a statistically independent predictor of mortality. Trial registration number CEIM 20/217

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Caminando en la ruta sentipensante: configuración de experiencias pedagógicas nivel inicial

494 páginasEste texto es realizado en el contexto del Plan de Desarrollo 2016 – 2020, “Bogotá mejor para todos”, en el que se señala: Bogotá es entendida como una ciudad educadora, en la que todos los ciudadanos son agentes educadores y todos los espacios pueden ser escenarios pedagógicos para el aprendizaje. Una ciudad educadora tiene como centro el conocimiento e inspira aprendizaje, formas y lenguajes para reconocernos, para reencontrarnos; los espacios para el aprendizaje son entendidos como espacios para la vida, en los que se posibilita la investigación y la innovación para vivir mejor, para reinventarnos como ciudad, una ciudad mejor para todos. Los dieciocho textos aquí presentados, fruto del acompañamiento pedagógico realizado por el IDEP en 2019, son base y referente para seguir aportando en la configuración y consolidación de comunidades de saber y práctica pedagógica de la ciudad, así como en la conformación de colectivos y redes de maestros. Son la evidencia de un potente trabajo de acompañamiento a experiencias de nivel inicial, caracterizadas por contar con ideas o avances para problematizar, estructurar, fundamentar, elaborar estrategias y un plan de acción